Neurosyphilis mimicking giant cell arteritis both clinically and microscopically.

Temporal arteritis is usually caused by giant cell arteritis (GCA). However, inflammation of the temporal artery can also occur secondary to autoimmune diseases or infections.We present a remarkable case of a man in his 70s with biopsy proven temporal arteritis, who was later diagnosed with meningovascular neurosyphilis. The presentation of an acute onset monocular vision loss with inflammation of the temporal artery on biopsy appeared a GCA, misleading the physicians, as it turned out to be a manifestation of neurosyphilis.